Abrasive cutting wheel



March 3, 1942. H. v. ALLISON ABRASIVE CUTTING WHEEL Filed Feb. 8, 1941 Hugh VflZ/z'son Patented Mar. 3, 1942 v ABRASIVECUTTING WHEEL Hugh V. Allison, Fairfield, ComL, assignor to The Allison Company, Bridgeport, Conn., a corporation oi Connecticut Application February a, 1941, Serial No. 377,997

6 Claims. (C

This invention relates to new and useful improvements in those abrasive cutting wheels ranging up to five thirty-seconds of an inch in thickness.

Abrasive cutting wheels at present manufacturedrange from a few thousandths of an inch to about three-eighths of an inch in thickness but the present invention relates only to such wheels as are not more than iive thirty-seconds of an inch in thickness since beyond such thickness the internal cutting wheel construction of the invention not only loses its advantages but in fact becomes detrimental.

An object of the invention is to provide an organic bonded thin abrasive cutting wheel having substantially evenly or uniformly distributed therethrough short lengths of metal fibres such as are known as metal wool and which fibres generally are not more than one-fourth of an inch in length and the cutting wheel being not greater than five thirty-seconds of an inch in thickness whereby said nietal fibres serve eiTectively to conduct heat from the interior to the side surfaces of the cutting wheel during use of the latter for dissipation to prevent overheating of the interior of the wheel and thereby prolong its useful life.

In the accompanying drawing:

Fig. 1 is a side elevational view of an abrasive cutting wheel made in accordance with the invention;

Fig. 2 is an edge elevational view of the wheel; and

Fig. 3 is an enlarged side elevational view of a portion of the wheel of the invention.

Heretofore it has been proposed to reenforce :2

if the wheel is operatedin a coolant but owing to the thickness of such a wheel the metal fragments or'the short pieces of wire serve to carry the generated heat to the interior of the large bodies with'the result that the heat is concentrated in the interiors of the bodies and weakens and bringsabout the premature destruction of the bonding materials of the wheels. As the bonding materials in these grinding wheels is thus ripheral edge of the wheel becomes concave durweakened the wheels wear away rapidly and thus their useful life is shortened. v

Manufacturers of abrasive cutting wheels have constantly sought and in fact are constantly seeking ways and means of manufacturing abrasive cutting wheels of greater useful life span. I have metal wool the useful life of the wheel is extended. Such metal fibres serve to conduct heat from the-interiors of the wheels to the side sun faces thereof for ready dissipation in the coolant through which said wheels usually operate. This prolongs the useful life of the wheels by prevent- .ing overheating and destruction of the bond in tion or composition but four thirty-seconds 0.

an inch in. thickness likewise retains a convex}: peripheral edge during use on similar materialt but the convex edge is less pronounced. Now wheri a wheel of the same composition but five thirty-seconds of an inch in thickness is used in the same way it develops aperipheral edge which is straight across. This straight across edge is retained by the five thirty-seconds of an inch wheel during-use and is the ideal edge fora cutting wheel although the convex edge is not objectionable.

When the thickness of the wheel is increased to as much as six thirty-seconds'of an inch the pcing use in the cutting of. steel, etc. and when the thickness of the wheel is further increased thedevelopement of the concave edge is accentuated. This concave or grooved edge is veiy detrimental in a wheel of the mentioned thickness as the weakened edge portions of the wheel at the sides of the groove break off whereby the edges of the wheel are not true and then the wheels tend to lead toward oneside or the other with the result that straight cuts through metal bars or the like are not obtained Additionally any work being acted on by such wheels is given a contour the reverse of thatof the edge of the wheel and therefore as the wheel becomes concave a ridge is piece.

raised on the work and the contour of th work changed.

The mentioned grooving of the cutting wheels during use when they are of a thickness greater than five thirty-secends of an inch results from the fact that the presence of the metal wool tends to generate extra heatover that which is generated when the wheels are without metal wool content. When the wheels are above the thickness named the metal fibres do not succeed in conducting the excessive heat from the interiors of the wheels to their sides for dissipation. On

, the contrary the metal wool conducts the heat the heat for dissipation. Thus when metal wool is incorporated in an'abrasive cutting wheel of less than five thirty-seconds of an inch in'thickness the metal wool is very beneficial and increases the life of the wheel from 30 to 40 percent depending on the materials, being cut.- On the contrary when such wool is incorporated in wheels of a thickness greater than five thirtyseconds of an inch the wool is detrimental to the life of the wheel.

In addition to the above use has shown that the presence of the metal fibres in a thicker wheel results in glazing and loading of the peripheral edge of the wheel during attempted use of the wheel as a cutting wheel. This loading and glazing of the peripheral edge of the wheel renders it useless as a cutting wheel. I have in an attempt to cut with such thicker wheels (a wheel threeeighths of an inch in thickness), containing metal fibres, stalled a five horse power motor without being able to force the wheel to cut through the When thewheel glazes or loads it simply rides in whateverportion of a cutmay have been made without any further cutting actionand apparently no amount of pressure will force it to out. In these thicker wheels the metal fibres cause the wheels to give to the surface of any portion of a cut that is made a poor finish in that such surface is scratched and rough and not smooth and finished as is desired in this work.

- The abrasive cutting wheel of the invention is prepared of a composition comprising abrasive grain, an organic bond and metal fibres or metal wool. and. the bond may contain fillers as is usual in the art. Natural or synthetic rubber may be used for the bond or it may comprise a resin and up until the presentsuch materials, because of their strength and ease of processing have proven the best for my purpose. kind and size depending on the work to be per- Abrasive grain of a formed by the cutting wheel is used. Where the themass and thus in the finished wheel. Generally the metal fibres following the milling operation do not exceed one fourth of an inch in length although in some instances a few fibres of greater lengthare to be found in the completed wheels.

Metal fibres or wool other than steel wool may be used for my purpose. Examples of such other metal fibres are fibres of stainless steel. of aluminum, of copper, and of brass, etc. The metal fibres may be incorporated in the mass from which the wheel is to be made in a manner difler-e ent fromthe milling of the metal woolinto the mass. If the metal wool is chopped into short lengths (generally not more than one-fourth of an inch) it may be uniformly distributed throughout a plastic mass by stirring. For example, the bonding agent may be dissolved into a stirrable mass and thereafter the choppedshort lengths of metal fibres may be stirred into the mass either alone or with the abrasive grain and other materials or before or after such other .materials have been added to the bond. The complete mass or mix is then shaped, dried-, pressed and vulcanized or otherwise cured in the usual manner. I

In the drawing the abrasive cutting wheel of the invention comprises a thin disc-like body Ill adapted to be mounted by a means (not shown) for rotating it at .high speed.' Usually these wheels are operated through a bath of water or other coolant. Distributed uniformly butv in random order through the body III are short lengths ll of metal wool. These metal fibres serve to conduct heat from'the interior of the body In to the side surfacesthereof for dissipation in the coolant and thus serve to prevent overheating of the portion' of the body intermediate its side surfaces.

When cutting metal, as steel bars, the wheels of the invention have about 30 percent more useful life than the same composition of wheels not containing the metal wool and in additionthere is less discoloration of the metal being cut. When cutting glass the useful life of the present wheel is in the neighborhood of 40 percent greater than the same composition of wheel without the metal wool. It is to be understood that the above references to percentages in the matter of the life of the wheels relates only to wheels of not more than five thirty-seconds of an inch in thickness.

Having thus set forth the nature of my inven- .prising abrasive. grain, metal wool fibres, and a bond securing the grain and wool fibres together in the disc, said wool fibres generally not more than one-fourth of an inch in length whereby they are uniformly distributed and disposed at random in said disc, and said disc not more than five thirty-seconds of an inch in thickness;

.2. In an abrasive cutting wheel, a disc: comprising abrasive grain, metal wool fibres, and a bond securing the grain and wool fibres together I in the disc, said wool fibres disposed at random in said disc, and said disc not more than five thirty-seconds of an inch in thickness.

3. In an abrasive cutting wheel, a disc comprising abrasive grain, metal wool fibres, and a rubber bond securing the grain and wool fibres together in the disc, said wool fibres disposed at random in the disc, and said disc not more than five thirty-seconds of an inch in thickness.

4. In an abrasive cutting wheel, a disc comprising abrasive grain, metal wool fibres and abond comprising a mixture of rubber and resin securing the grain and metal wool fibres together in the disc, said wool fibres disposed at random in said disc, and said disc not more than five thirty-seconds of an inch in thickness.

6. The method of making an abrasive cutting wheel comprising milling abrasive grain and metal wool fibres into a bonding material on a roll mill whereby to distribute the grain and wool fibres in the bonding material and reduce the lengths of the metal wool fibres. sheeting the milled mixture or abrasive grain, metal wool fibres and bonding material, cutting discs therefrom, and curing said discs.

HUGH V. ALLISON. 

